
  a {
    position: relative;
    width: 100px;
    height: 60px;
    text-align: center;
    line-height: 60px;
    margin: 45px;
    text-decoration: none;
    color: aqua;
    font-size: 20px;
    padding: 10px 30px;
    text-transform: uppercase;
    transition: 0.5s;
    overflow: hidden;
    -webkit-box-reflect: below 1px linear-gradient(transparent, #1113);
  }
  a::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 20px;
    height: 20px;
    border-top: 2px solid aqua;
    border-left: 2px solid aqua;
    transition: 0.5s;
    transition-delay: 0.5s;
  }
  a::after {
    content: '';
    position: absolute;
    bottom: 0;
    right: 0;
    width: 20px;
    height: 20px;
    border-bottom: 2px solid aqua;
    border-right: 2px solid aqua;
    transition: 0.5s;
    transition-delay: 0.5s;
  }
  a:hover::before, a:hover::after {
    width: 100%;
    height: 100%;
    transition-delay: 0s;
  }
  a:hover {
    background-color: aqua;
    color: #000;
    box-shadow: 0 0 50px #21ebff;
    transition-delay: 0.3s;
  }
  /* a:nth-child(1) {
    filter: hue-rotate(150deg);
  } */
  /* a:nth-child(3) {
    filter: hue-rotate(270deg);
  }
  a:nth-child(4) {
    filter: hue-rotate(400deg);
  }
  a:nth-child(5) {
    filter: hue-rotate(70deg);
  } */